How much data do I need to collect?
Sorry but no one can give you a number. 

As stated already in the comment by Manngo, the general rule: is as much as you can. I have also seen the 10x number being thrown around, see here. According to this "rule", you need  roughly 10 times as many examples as there are degrees of freedom in your model.

How much data you will need is something you can only answers to through empirical investigation. The amount of data you need to collect is influenced by the complexity of the data, the dimensionality of the data and the algorithm you intend to train(although this can be controlled somewhat through regulirazation, see this good blog post by Jake Vanderplas for more information). 

This question  might be of interest to you.